SYSTEM AND METHOD FOR CELL BALANCING AND CHARGING

• US 20100295510A1
• Filed: 05/13/2010
• Published: 11/25/2010
• Est. Priority Date: 05/22/2009
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Inventors: MOUSSAOUI, ZAKI, ALLEN, TONY
• Granted Patent: US 8,541,980 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An apparatus for charging a plurality of series connected battery cells includes first and second input terminals for providing a charging voltage to the plurality of series connected battery cells. A transformer includes a primary side associated with the charging voltage and a secondary side including a plurality of portions. Each of the plurality of portions connected across at least two of the plurality of series connected battery cells. A first switch in series between each of the plurality of portions of the secondary side and a first battery cell of the at least two of the plurality of series connected battery cells provides a charging current to the first battery cell during a first portion of a cycle of a current in the primary side of the transformer. A second switch in series between each of the plurality of portions of the secondary side and a second battery cell of the at least two of the plurality of series connected battery cells provides a charging current to the to the second battery cell during a second portion of the cycle of the current in the primary side of the transformer.

Claims

1. An apparatus for charging a plurality of series connected battery cells, comprising:

first and second input terminals for providing a charging voltage to the plurality of series connected battery cells;

a transformer including a primary side associated with the charging voltage and a secondary side including a plurality of portions, each of the plurality of portions connected across at least two of the plurality of series connected battery cells;

a first switch in series between each of the plurality of portions of the secondary side and a first battery cell of the at least two of the plurality of series connected battery cells for providing a charging current to the first battery cell during a first portion of a cycle of a current in the primary side of the transformer; and

a second switch in series between each of the plurality of portions of the secondary side and a second battery cell of the at least two of the plurality of series connected battery cells for providing a charging current to the second battery cell during a second portion of the cycle of the current in the primary side of the transformer.

2. The apparatus of claim 1, wherein in a charging mode charge on the primary side is transferred to the plurality of portions of the secondary side, the voltage from the primary side divided amongst the plurality of portions of the secondary side in proportion to an amount of charge needed by the first or second battery cell associated with the portion of the secondary side and in a discharging mode an input to the primary side of the transformer comprises a total series voltage of the plurality of series connected battery cells.

3. The apparatus of claim 1 further including a resonant circuit connected between the primary side of the transformer and the first and second input terminals.

4. The apparatus of claim 3 further including a switching circuit, the switching circuit comprising:

a first switch connected between the first input terminal and the resonant circuit; and

a second switch connected between the second input terminal and the resonant circuit.

5. The apparatus of claim 3 further including:

a first diode connected between the first input terminal and the resonant circuit; and

a second diode connected between the second input terminal and the resonant circuit.

6. The apparatus of claim 1, wherein the first switch and the second switch comprise a MOSFET transistor.

7. The apparatus of claim 1, wherein each of the plurality of portions of the secondary sides are connected with a first polarity across the first battery cell and with a second polarity across the second battery cell.

8. The apparatus of claim 1, further including a diode associated with the first switch and the second switch for providing a charging current to the first battery cell and the second battery cell.

9. An apparatus for charging a plurality of series connected battery cells, comprising:

first and second input terminals for providing a charging voltage to the plurality of series connected battery cells;

a transformer including a primary side associated with the charging voltage and a secondary side including a plurality of portions, each of the plurality of portions connected across at least two of the plurality of series connected battery cells;

a first diode in series between each of the plurality of portions of the secondary side and a first battery cell of the at least two of the plurality of series connected battery cells for providing a charging current to the first battery cell during a first portion of a cycle of a current in the primary side of the transformer; and

a second diode in series between each of the plurality of portions of the secondary side and a second battery cell of the at least two of the plurality of series connected battery cells for providing a charging current to the to the second battery cell during a second portion of the cycle of the current in the primary side of the transformer.

10. The apparatus of claim 9, wherein in a charging mode charge on the primary side is transferred to the plurality of portions of the secondary side, the voltage from the primary side divided amongst the plurality of portions of the secondary side in proportion to an amount of charge needed by the first or second battery cell associated with the portion of the secondary side and in a discharging mode an input to the primary side of the transformer comprises a total series voltage of the plurality of series connected battery cells.

11. The apparatus of claim 9 further including a resonant circuit connected between the primary side of the transformer and the first and second input terminals.

12. The apparatus of claim 11 further including a switching circuit, the switching circuit comprising:

a first switch connected between the first input terminal and the resonant circuit; and

a second switch connected between the second input terminal and the resonant circuit.

13. The apparatus of claim 11 further including:

a first diode connected between the first input terminal and the resonant circuit; and

a second diode connected between the second input terminal and the resonant circuit.

14. The apparatus of claim 9, wherein each of the plurality of portions of the secondary sides are connected with a first polarity across the first battery cell and with a second polarity across the second battery cell.

15. A method for charging a plurality of series connected battery cells, comprising the steps of:

receiving a charging voltage for the plurality of series connected battery cells;

transferring the charging voltage from a primary side of a transformer to a plurality of portions of a secondary side;

charging a first half of the plurality of series connected battery cells using the plurality of portions of the secondary side during a first portion of a cycle of a current in the primary side of the transformer; and

charging a second half of the plurality of series connected battery cells using the plurality of portions of the secondary side during a second portion of a cycle of a current in the primary side of the transformer.

16. The method of claim 15, wherein the step of charging a first half of the plurality of series connected cells further comprises the steps of:

connecting the first half of the plurality of series connected batteries to the plurality of portions of the secondary side during the first portion of the cycle of the current in the primary side of the transformer;

disconnecting the second half of the plurality of series connected batteries from the plurality of portions of the secondary side during the first portion of the cycle of the current in the primary side of the transformer; and

charging the first half of the plurality of series connected batteries during the first portion of the cycle of the current in the primary side of the transformer.

17. The method of claim 15, wherein the step of charging a second half of the plurality of series connected cells further comprises the steps of:

connecting the second half of the plurality of series connected batteries to the plurality of portions of the secondary side during the second portion of the cycle of the current in the primary side of the transformer;

disconnecting the first half of the plurality of series connected batteries from the plurality of portions of the secondary side during the second portion of the cycle of the current in the primary side of the transformer; and

charging the first half of the plurality of series connected batteries during the first portion of the cycle of the current in the primary side of the transformer.

18. The method of claim 15 further including the step of generating a resonant input to the primary side of the transformer responsive to the charging voltage.

19. The method of claim 18 further including step of switching the charging voltage to a resonant circuit providing the resonant input.

20. The method of claim 15, wherein the steps of charging further comprises the steps of switching the polarity of the voltage from the plurality of secondary sides of the transformer when switching between charging the first half and the second half of the plurality of series connected cells.